I have long been of the opinion that I would never get the enjoyment that other people got from rereading a fiction book. I thought that my memory of the book would be too good to really let me enjoy the book in the same way twice and I should just read some other book which I had never read before.
But I started to hold this opinion when my reading life only had say 5 good years behind it. So every book I had ever read was relatively fresh on my mind. But now I realize that of course my memory isn't nearly so good as I give it credit for. I have been rereading the keys to the kingdom books by Garth Nix.
The books are relatively short and I wanted to get the details of the books straight in my memory again before reading the last two books in the series. But as I have been reading the books it has become abundantly clear that not only had I forgotten the details of the books but had in essence forgotten the whole story.
While it is true that I generally remember what is going to happen a couple of pages or a couple of paragraphs before it happens I don't think that really diminishes the enjoyment of reading the book very much. Especially since now the relevance of details that passed me by on a first reading are now clear.
So I have changed my mind, rereading any type of book be it fiction or non-fiction is aok by me.